In a current fulfillment system, it is needed to first retrieve an item ordered by a customer from its storage position (e.g., on a shelf) and then put it in a bin or a cart. After all items in a same set of orders are retrieved from their storage positions, the bin or cart holding these items will be sent to a sorting station where the items in the bin or cart will be sorted based on individual customer orders and the sorted items may be packaged.